Hydraulic shock absorbers, for example those of the monotube type widely used in motor manufacturing and other industries, are intended to operate at relatively high hydraulic pressures, of around 20 bar on average, with peaks of as much as 100 bar. Because of these high operating pressures, the seal for the pressurized fluid (usually oil) contained in the shock absorber body, which opposes the reciprocating motion of the piston in the body during use, and the guide for the shock absorber rod are provided by means of a guiding and sealing unit having a bushing that is engaged with the rod which passes through it, and which is then fitted in a fluid-tight manner within the shock absorber body, and a sealing assembly carried by the bushing.
An example of a guiding and sealing unit of this type is described in the German utility model published under the number DE8201327U.
This prior art guiding and sealing unit includes numerous elements to be fitted separately, and is therefore relatively bulky and difficult to fit, while its performance is not entirely satisfactory; these drawbacks are particularly serious in view of the desire to reduce the overall dimensions and weight of shock absorbers for a given working stroke.